1. Field of the Invention
This invention relates to the field of surface preparation, particularly to the field of surface preparation of rubbers to increase their wettability.
2. Description of the Prior Art
Lithographic printing depends upon the acceptance by the printing plate of ink at certain hydrophobic sites and its rejection at hydrophilic locations. The hydrophilic sites are occupied by water which is provided by a dampener roll which brings water ("fountain solution") to the surface of the plate. Unfortunately, dampener rolls are made of elastomers which are relatively low in wettability and thus poorly receptive to water.
In order to increase the wettability of the rubber surface of the dampener roll and thus provide more water to the plate, a wide variety of additives and roll treatments have been employed. One of the best is sulfuric acid etching of the roller. However, acid etching is not effective for many dampener roller materials and it degrades some materials such as polyurethanes. Additionally, acid etching provides only a limited increase in the wettability of the surface of those materials for which it is effective.